The paradoxical evolution of sensor SNR over time

In summary, DSLR sensor technology has made significant advances over the past
several years, with full-frame sensors outpacing the progress of APS-C sensors.
DxOMark Measurements show that advances in RAW conversion technology have
compensated for the increase in SNR brought about by the proliferation of
smaller, less light-sensitive pixels in DSLRs, with the result that today’s
high-resolution cameras produce higher-quality images overall than low-resolution
cameras when viewed or printed under the same conditions.